Beginning on December 28, 1968, San Francisco's bay area became home for one of America's most
notorious serial killers -- the elusive Zodiac killer. Teasing and taunting the police with telephone calls, letters and
cryptic messages, the Zodiac continued on his killing spree seemingly unheeded for almost three years. While claiming
that he had killed thirty-seven people, police could only link him to a handful of attacks for certain. Between 1969 and 1974,
the Zodiac communicated with various newspapers and demanded that his letters be printed or reprisal killings would occur.
On July 31, 1969, one such letter included a three part cipher, with each part being sent to a different San Francisco
area newspaper. Complying with the killer's demand, the three newspapers ran the story of the Zodiac cipher. Up to that
point, the government's best code breakers had been unable to crack the cipher. Seeing the crypt-o-gram style cipher in
the newspaper, Don Harden, a local high school teacher from Salinas, sat down with his morning cup of coffee and within
a few hours he and his wife solved the cipher. Harden's break came when he started with an assumption that the killer's ego
might cause him to begin his message with the letter "I" and that he would most likely be using the words "kill" and "killing"
both of which contain a double-L. His assumptions proved correct, and the cipher soon began to form an erie confession of
sorts. The solved message began, "I like killing people because it is so much fun. It is more fun than killing wild game
in the forrest because man is the most dangeroue anamal of all" (misspellings in original).

First part of Zodiac cipher that was solved by a local high school teacher

Using a simple letter substitution cipher made it easy to solve the Zodiac's July 1969 message. Police and the public
would not be so lucky the next time, and they didn't have to wait long. On November 9, 1969, the Zodiac sent what has
become known as the "340 Cipher" (for the 340 cryptic characters that it contains). The California Department of
Justice, the FBI, the Office of Naval Intelligence, the U.S. Postal Service, and local bay area police departments, as
well as many professional code breakers, have been unable to solve this cipher and it remains unsolved
to this day.

The Zodiac's unsolved 340 cipher

In mid-1974, the Zodiac wrote his last letter to the media. He would never be heard from again. In 2004, the San Francisco
Police Department offically re-classified the Zodiac case status from "active" to "inactive." True to the Zodiac's
prediction, made over 35 years ago, that he would never be caught -- he never was. His identity and the solution to the
340 Cipher both remain a mystery to this day.

"The police shall never catch me because I have been too clever for them."
-- the Zodiac killer

If you like puzzels and crypt-o-grams, take a crack at solving the Zodiac's 340 Cipher. The person who discovers the
solution is almost certain to become internationally famous overnight.

Note: The Zodiac is known to intentionally misspell words and uses bad grammar in order to avoid identification and to
presumably throw off professional code breakers.